JP2014506031A - Diagnostic engine for determining global line characteristics of a DSL telecommunications line and method of using the diagnostic engine - Google Patents

Abstract

  A diagnostic engine for remotely determining the global line characteristics of an xDSL telecommunications line from the access node location. The diagnostic engine is configured to measure first, second, and third line characteristics, respectively, according to three separate measurement techniques such as MELT, SELT, and DELT, first, second, and Preferably, third measurement means is included. The diagnostic engine further includes a combination means that can combine the measured line characteristics to derive information related to the global line characteristics, or the physical state of the line as well as possible outcomes to the DSL service. By combining the three measurements in the combination means, the resulting global line characteristics of the line are improved compared to performing the interpretation of the three measurements separately.

Description

  The present invention relates to a diagnostic engine for remotely determining the global line characteristics of a telecommunication line at the end of the line.

  With the growing market development of IPTV solutions, video-on-demand offerings, or triple play services, for example, both system performance and customer support are even more demanding on xDSL.

  As a physical link, xDSL telecommunications lines, which typically transport information over wire lines to end users, are known as bottlenecks in quality of service, and network analyzer software products can remotely locate the source of physical problems. Used for both diagnosing and taking measures to improve performance. The diagnostic engine preferably forms part of the network analyzer software application and is typically embedded therein.

  Such a diagnostic engine helps the operator troubleshoot problems that occur in the physical layer. To that end, various measurement techniques or analysis methods have been developed for measuring line parameters or line characteristics in order to derive information related thereto from the global line characteristics of the telecommunication line.

  For example, one-end line measurement techniques or physical layer analysis techniques already exist. For decades, metal test heads have been able to provide line electrical parameters (eg, differential voltage / current, common mode voltage / current, line parameters, line termination, within the telephone's frequency bandwidth. Have provided a way to estimate impedance, etc.). Thus, this method of providing a one-end line test solution within a narrow bandwidth is known as a metal line test MELT or narrowband line test NBLT solution.

  In practice, as shown in FIG. 1, in addition to a direct metal connection that may be established between each of the two wire wires, TIP and RING, a binder shield GND connected to ground potential, and a metal test System exists. Metal testing provides a solution for 3-wire measurement.

The advantage of such a test setup is that the AC and DC voltages / currents between each of the three wire pairs, ie V _tip-ring , I _tip-ring , V _tip-gnd , I _tip-gnd , V _{ring− gnd} and I _ring-gnd can be collected. This allows estimation of model parameters for narrowband lines, such as resistance and capacitance, and their termination impedance and insulation resistance.

Knowledge of these measured line characteristics makes it possible to estimate the following physical or global line characteristics of the telecommunication line:
-Loop length (knows capacitance by length),
-Loop termination (telephone, open line, short circuit, operator specific termination device),
-Detection of specific faults (1-wire open fault, short circuit, etc.),
-The presence of undesirable line properties (low common mode isolation, unbalanced loops, etc.).

  However, since this metal line test MELT supports low frequency signals (larger wavelength compared to the loop length), only low frequency circuit line characteristics can be obtained. However, inferences about the electrical properties that also affect the DSL frequency band and thus affect DSL service, eg, open wire inferences, can be made.

  In order to investigate what happened in the DSL frequency band, another measurement technique or physical layer analysis technique based on the reflectance method may be used. This is a single-ended line test SELT that analyzes wave reflections in the entire DSL frequency spectrum (the SELT-PMD for measurement techniques and the SELT-P for interpretation / analysis on it respectively) ITU-G.996.2, but this document discusses SELT measurement to use both measurement and interpretation to summarize the information provided by the test technique) .

  As shown in FIG. 2, the single-ended line test SELT is a reflectometry measurement performed between a given pair of two-wire wires. The analysis signal passes through a coil transformer with galvanic isolation and no common mode parameters can be collected, limiting the measurement to differential mode only. Furthermore, the transformer serves as a high-pass filter that prevents any DC component from being measured. However, the advantage of the SELT technique is the ability to more reliably estimate the loop length or detect some faults and locate them.

  Compared to the MELT technique, SELT provides a reliable estimate of the location of the fault, even in the presence of a short circuit. Also, complex loop topologies or loop phenomena that exhibit properties in the DSL frequency when a bridge tap is present can be identified using this type of measurement technique.

  In contrast, the reliability of the line characteristics measured with SELT decreases with loop length, especially for loops longer than 3 km, while MELT still provides a stable estimate. Also, the SELT method is more difficult or even difficult to detect the termination type when it requires a common mode voltage / current, such as in the case of an accident to ground.

  Dual-ended line test DELT measurement techniques also exist to diagnose problems using line operating parameters and directly quantify their impact on DSL service. The DEL measurement is performed by the xDSL modem itself when the line is in use or just before the line goes into use during the initialization phase. DEL therefore requires the connection of a modem to the line as well as the presence of a DSL service. When the line is disconnected or when the subscriber premises equipment CPE is not present, line characteristic measurements are not available.

  In summary, each of these three measurement techniques provides a solution for estimating several electrical parameters or line characteristics. The capabilities of the three techniques have their own advantages, however, those advantages are complementary.

  Each type of measurement technique is implemented on its own, involving experts to manually obtain the necessary analysis to obtain the global line characteristics of the telecommunications line, and different measured line characteristics. Collect and combine them.

ITU-G. 996.2

  The object of the present invention is an improved diagnostics configured to enhance quality of service by improving the breadth of capabilities and the reliability of the estimation, which leads to easier advanced troubleshooting. Is to provide an engine.

According to a characteristic embodiment of the diagnostic engine, this object is achieved by the diagnostic engine comprising:
First measuring means configured to measure a first predetermined line characteristic according to a first measuring technique;
A second measuring means configured to measure a second predetermined line characteristic according to a second measurement technique; and a first predetermined measured value to derive from it a global line characteristic of the telecommunication line Combination means configured to combine the line characteristic and the second predetermined line characteristic.

  In this way, the presence of two separate measurement means, and their combination means in the diagnostic engine not only improves service quality, but also no longer involves expert intervention for advanced troubleshooting. The absence saves money and time.

  Contrary to the above independent measurement method, which typically requires manual inspection by a specialist, the diagnostic engine may be used by less skilled technicians. Since the fault is located, the field force can be driven directly at the correct location. This overall results in an accelerated xDSL line maintenance process and reduced costs.

  Another characteristic embodiment of the diagnostic engine is that the measurement technique is selected from a metal line test MELT, a single-ended line test SELT, and a dual-ended line test DELT.

  Using two of these advanced measurement techniques for problems that affect DSL lines allows for a combination of root cause analysis, failure localization, and service impact.

  In another characteristic embodiment, the diagnostic engine further comprises a third measuring means configured to measure a third predetermined line characteristic according to a third measuring technique, the combining means comprising: In order to derive the global line characteristics of the line therefrom, the measured first predetermined line characteristic, second predetermined line characteristic, and third predetermined line characteristic are combined.

  In this way, three separate measurement techniques may be automatically applied over the same problematic telecommunication line. Predetermined line characteristics or measurement results are then combined simultaneously by the combining means to provide global line characteristics that indicate an accurate diagnosis of the physical state of the line and possible outcomes to the DSL service.

  The invention also relates to a method for remotely determining the global line characteristics of a telecommunications line at the end of the line.

The method is preferably used by the diagnostic engine described above, the method comprising the following steps:
Measuring a first predetermined line characteristic according to a first measurement technique;
Measuring a second predetermined line characteristic according to a second measurement technique; and- measuring a first predetermined line characteristic and a second predetermined to derive a global line characteristic of the line therefrom Step to combine the line characteristics.

  In this way, by measuring two separate line characteristics, and combining them, a very accurate and reliable global line characteristic can lead to localization of the problem, its possible root cause, and DSL service. Can be provided for its impact on

In a preferred characteristic embodiment, the method further comprises the following steps:
Measuring a third predetermined line characteristic according to a third measurement technique; and- measuring a first predetermined line characteristic, a second predetermined to derive a global line characteristic of the line therefrom Combining the third line characteristic and the third predetermined line characteristic.

  Thereby, three different measurement techniques are applied with the advantages mentioned above with respect to the diagnostic engine implementing the technique.

  Further characteristic embodiments of the diagnostic engine and the method used herein are mentioned in the appended claims.

  It should be noted that the term “comprising” or “including” as used in the claims should not be construed as limited to the means listed therein. Accordingly, the scope of expressions such as “a device including means A and B” should not be limited to embodiments of devices consisting solely of means A and B. For embodiments of the present invention, it means that A and B are essential means of the device.

  Similarly, it should be noted that the term “coupled”, also used in the claims, should not be construed as limited to direct connections only. Thus, the scope of expressions such as “device A coupled to device B” should not be limited to device embodiments in which the output of device A is directly connected to the input of device B. That means that there may be a path between the output of A and the input of B, and that path may include other devices or means.

  The above and other objects and features of the invention will become more apparent and the invention itself will be best understood by referring to the following description of embodiments in conjunction with the accompanying drawings.

FIG. 2 shows a diagnostic engine operating according to a first measurement technique (MELT / NBLT). FIG. 2 shows a diagnostic engine operating according to another measurement technique (SELT). FIG. 2 shows a diagnostic engine according to an embodiment of the invention and operating according to two separate measurement techniques (SELT, MELT). FIG. 2 shows a telecommunication line with a short circuit in the middle of a loop to be detected by a diagnostic engine. FIG. 3 shows a telecommunication line with an operator premises signature to be detected by a diagnostic engine. FIG. 2 shows a telecommunication line with a short to ground in the middle of a loop to be detected by a diagnostic engine. FIG. 2 shows a telecommunication line with a one-wire wire open fault to be detected and located by a diagnostic engine.

  The diagnostic engine shown in FIG. 3 is used to build global circuit characteristics, or circuit physical state / characteristics, as a result of automatically combining the results of different measurement techniques such as DELT, SELT, and MELT. The As a result, the diagnostic engine can provide accurate information about the physical root cause of the problem, its localization, and its impact on DSL service.

  In the first embodiment, the diagnostic engine typically launches two types of analysis performed by a device located at a telecommunications access node location, eg, DSLAM, and is an advantage from their complementary benefits. And combine the results of the analysis to expand the analytical capabilities and in addition improve the reliability of the conclusions.

  More specifically, the diagnostic engine remotely determines the global line characteristics of the telecommunication line, preferably the DSL telecommunication line, at the access node DSLAM. The other end of the xDSL line is coupled to a telephone and / or DSL subscriber premises equipment CPE. If both are present, a splitter is used to separate the signals.

For this purpose, the diagnostic engine includes:
A first measurement means capable of applying a first measurement technique, eg a metal line test MELT or a narrowband line test NBLT, to the line;
-A second measurement technique, for example a single-ended line test or reflectivity method SELT, which can be applied to the line; and
-Combine the results of the two types of measurements to provide a test solution with an enhanced combination coupled to the first measurement means and the second measurement means that can expand the capability of the one-line circuit test. Combination means CM that can.

  The first measuring means and the second measuring means are preferably configured to operate simultaneously or sequentially.

  The first measurement means or the second measurement means may also use another measurement technique as a physical layer analysis technique, such as a dual-ended line test DELT configured to measure the operating properties of the wire line, Note that it may be designed to apply to:

  Furthermore, any combination of the above two measurement techniques, SELT, MELT, or DELT may be applied.

The line test solution provided by the diagnostic engine offers wider and more confident possibilities resulting from an “intelligent” combination of complementary measurements such as:
-Loop end (even for long loops),
The type and location of the fault (even for long loops),
-Improved estimation of loop length (even for long loops),
-Increased confidence in properties commonly identified by two or more techniques;
-Improved MELT conclusions in the presence of bridge taps or complex topologies.

  Note that a diagnostic engine that is typically embedded in a network analyzer software product is remotely located on the server. The first task of the diagnostic engine, and more particularly its combination means CM, is to contact the DSLAM and collect measured data or predetermined line characteristics prior to their use for combined diagnosis or electrical To provide global line characteristics of communication lines and improved line characteristics.

  The single-ended line test SELT shown in FIG. 2 accurately quantifies the service impact with very limited information about the type of problem (open or short only) when the line is not in use. Used to locate problems without ability.

  The SELT measurement is performed through a high-pass filter, ie, a transformer coupled to a pair of wires at the end of the xDSL telecommunication line, and the binder shield of the xDSL line is further connected to ground potential.

  SELT is actually a reflectometry measurement performed by a modem located at the access node. Like any other reflectometry system, it consists in transmitting the incident signal over the line and observing the signal reflection (echo).

  Since this measurement requires interruption of the service to be activated, it is usually performed on a disconnected line where the service has already been interrupted. The resulting measured line characteristics may be presented graphically by a reflectance distribution, eg, a plot showing the amplitude of the reflected signal (echo) as a function of distance. According to transmission line theory, any impedance change will produce a signal reflection, so any kind of fault on the line (open circuit, short circuit, bridge tap, gauge change, etc.) will be reflected in the reflectance distribution at the fault distance. Will produce a local maximum.

  This SELT technique is very powerful in locating some problems, but it is weak to speculate about the nature of the failure and its potential impact on DSL service.

  The metal line test MELT technique shown in FIG. 1 is actually a legacy test system that has been used on telephone lines for decades, but is still embedded in DSL equipment.

  The MELT measurement, also known as the narrowband line test NBLT measurement, is performed through a low pass filter having a TIP terminal and a RING terminal coupled to a pair of wires at the end of the xDSL line through separate coils and switches. In addition to the two coils, the low pass filter includes a capacitor coupled across the ends of these coils. The binder shield of the xDSL telecommunications line is further connected to the ground potential via the GND terminal.

  The MELT measurement is performed in the telephone bandwidth (DC to a few kHz) and consists in measuring several physical line parameters or line characteristics, such as DC voltage or resistance between wires and capacitance.

  Contrary to SELT and DELT (described below), MELT may also be implemented in a common mode, i.e., measuring the characteristics between the single wire of the line and ground. Thanks to this unique advantage, MELT can be used to diagnose several types of problems very accurately. For example, the MELT can distinguish between two wire wires and clearly identify which is cut. However, MELT has limited localization capability (eg, open circuit localization via capacitance measurement, but short circuit localization is not possible), and because of its very limited bandwidth, There is little way to determine what effect this will have on the potential DSL service running on the line.

  The MELT results are displayed with relatively limited localization information (only open circuits are located) and no information about the impact of DSL service is displayed.

  Four typical failure cases are described below as examples to demonstrate the strength of the diagnostic engine.

  In the first example shown in FIG. 4, there is a short circuit in the middle of the loop. Electrically, the differential impedance is dominated by a very low impedance created by a short that conveys a very low differential impedance (limited to wire impedance). Also, it becomes impossible to measure only the common mode capacitance of each wire separately. Thus, when using only the MELT solution, the different capacitance estimates remain in error and a reliable fault location cannot be calculated. On the other hand, when the reflectance method SELT is used, the propagation of electromagnetic waves exists in the line medium up to the position of the failure where reflection occurs according to electromagnetic theory. The reflected wave undergoes a 180 degree phase shift and returns to the reflectance method generator module. It is therefore possible to estimate the nature of the fault, i.e. a short circuit, and locate it.

  The second example deals with detection of operator premises signatures. For simplicity and from an electrical point of view, this type of device adds only extra impedance to the differential component at the operator premises prior to the splitter. This is shown in FIG. Using the metal test solution MELT, if each common mode impedance shows the same expected result for the first time compared to the differential impedance, it is quite possible to infer about the presence of extra impedance on the loop termination side. Be prominent and give clues about the presence of devices connected to the line. This accurate measurement of impedance can even identify operator equipment signatures. When performing reflectance analysis SELT, the presence of this extra impedance is interpreted from the SELT module as a longer loop estimate because only differential measurements are available and comparison to common mode is not possible. It's okay. To make matters worse, if this device contains a non-linear component, such as a diode, it requires a DC differential current to detect that component that cannot pass through the coil transformer and is therefore measured by the SELT module. I don't get it.

  The third example presents a fault that requires two combined approaches, MELT and SELT, to detect and locate. In fact, in the short-to-ground fault case, one wire of the pair is bound to the binder shield somewhere between the access node or DSLAM of the circuit and the customer end, as presented in FIG. Short circuit to In this case, the MELT solution detects the presence of such a fault, but cannot locate it. In contrast, SELT cannot conclude about the existence of this type of failure, but can locate the problem at a given length.

  Finally, in the fourth example of a one-wire open failure shown in FIG. 7, each test approach is appropriate for detecting and locating this type of problem. However, the use of the two solutions makes it possible to identify the fault type and locate it with a higher degree of confidence, especially when the fault occurs at a long distance. Thus, the use of combining the two results leads to a more credible conclusion.

  The different fault types and the methods used to detect them are outlined in Table 1 below. The table shows which method is most suitable for detecting a fault according to the type of fault. Also, the combined measurements appear to improve the overall information related to global line characteristics while using the measurement methods separately.

好ましい実施形態（図示せず）において、診断エンジンは、第３の測定技法、たとえば、デュアルエンド回線テストＤＥＬＴを、ｘＤＳＬ電気通信回線に適用することができる第３の測定手段をさらに含む。

In a preferred embodiment (not shown), the diagnostic engine further includes a third measurement means that can apply a third measurement technique, eg, a dual end line test DELT, to the xDSL telecommunication line.

  The combination means CM then derives information relating to the state of the telecommunication line from which the measured first line characteristic, second line characteristic, and second 3 line characteristics are combined.

  The dual-end line test DELT measurement is performed by the xDSL modem itself when the line is in use or just before the line enters use during the initialization phase. The resulting measured line characteristics may be stored in the modem device and polled by software having access to the operator management network. Since measurements are made by the modem itself, DELT is only available when the modem is connected to the line on both sides and has been in use for some time. When the line is disconnected or when the subscriber premises equipment CPE is not present, those measurements are not available or make no sense.

  DELT is used to detect problems in the physical layer and quantify their impact on services.

  Measurements are taken in the xDSL band (typically 20 kHz to a few MHz, depending on the type of xDSL technology), which can be used to quantify the impact of problems on xDSL services that should function within the same frequency band. Make the measurement very useful.

  An example of improved or global circuit characteristics of a DSL telecommunications line obtained by the combined three measurement techniques is described below by referring again to FIG. Alternatively, somewhere in the middle of the line between the DSLAM and the customer, one of the twisted two-wires is shorted to ground due to an accident.

In this example, the measurements obtained by each technique will convey the following results:
-MELT will detect a short circuit between one of the two-wire wires and ground (even identify which wire is affected) and does not include any localized information or service effects.
-SELT will detect an unknown default, but will accurately determine the distance between the fault and the central office. The impact of the service is estimated vaguely, and in addition, DELT will detect an unbalanced loop by detecting an increase in crosstalk level. This excessive crosstalk will be quantified in terms of bit rate effects (loss of x kbps). However, the root cause and localization of the problem with DELT itself is unknown.

  The combination of measurements taken by the three measurement techniques makes it possible to identify and locate defaults and quantify the impact of that service.

When such a problem occurs, a typical tool that can only perform separate or single DELT, SELT, or MELT measurements, ie, without a combined measurement engine or combination means CM, is as follows: Will provide unique line characteristics:
An unbalanced loop resulting in a 4 Mbps bit rate loss (from DELT);
-An unknown fault at 1 km from the central office (from SELT) or-An insulation fault between wire A and ground (from MELT).

The diagnostic engine can now further combine all these measurements with a single measurement engine CM. As a result, output messages that display information related to the state of the telecommunication line or global line characteristics are as follows:
A short circuit between wire A and ground located 1 km from the central office, resulting in a 4 Mbps bit rate loss.

  The same unambiguous information related to global line characteristics may be obtained from any other combined measurement. For example, a single wire open failure as shown in FIG. 7 where one of the two wires is open, a wire crossing as shown in FIG. 4 due to a short circuit between different pairs of wires, a degraded contact, etc. By default, a combined measurement may be applied.

  A final note is that embodiments of the present invention are described above in terms of functional blocks. From these functional descriptions presented above, it will be apparent to those skilled in the art of designing electronic devices how these block embodiments can be fabricated with well-known electronic components. I will. Thus, the detailed architecture of the functional block contents is not shown.

  While the principles of the invention have been described above with reference to specific devices, the description is merely an example and is directed to the scope of the invention as defined in the appended claims. It should be clearly understood that this is not done as a limitation.

Claims (14)

A diagnostic engine for remotely determining the global line characteristics of a telecommunications line at the end of the line,
First measuring means configured to measure a first predetermined line characteristic according to a first measuring technique (MELT / SELT / DELT);
A second measurement means configured to measure a second predetermined line characteristic according to a second measurement technique (SELT / MELT / DELT);
Combining means configured to combine the measured first predetermined line characteristic and the second predetermined line characteristic to derive a global line characteristic of the telecommunication line therefrom, Diagnostic engine. The diagnostic engine of claim 1, wherein the first measurement technique is a metal line test (MELT) and the second measurement technique is a single-ended line test (SELT). . The diagnostic engine of claim 1, wherein the first measurement technique is a metal line test (MELT) and the second measurement technique is a dual-ended line test (DELT). . The diagnostic of claim 1, wherein the first measurement technique is a single-ended line test (SELT) and the second measurement technique is a dual-ended line test (DELT). engine. The diagnostic engine further includes a third measuring means configured to measure a third predetermined line characteristic according to a third measuring technique (DELT / MELT / SELT); and , Configured to combine the measured first predetermined line characteristic, the second predetermined line characteristic, and the third predetermined line characteristic to derive the global line characteristic of the line therefrom The diagnostic engine according to claim 1, wherein:   The diagnostic engine according to claim 1, wherein the end of the telecommunications line is located at a telecommunications access node location.   The diagnostic engine according to claim 1, wherein the telecommunication line is a DSL telecommunication line. A method for remotely determining the global line characteristics of a telecommunications line at the end of the line,
Measuring a first predetermined line characteristic according to a first measurement technique (MELT / SELT / DELT);
Measuring a second predetermined line characteristic according to a second measurement technique (SELT / MELT / DELT);
Combining the measured first predetermined line characteristic and the second predetermined line characteristic to derive the global line characteristic of the line therefrom. 9. The method of claim 8, wherein the first measurement technique is a metal line test (MELT) and the second measurement technique is a single-ended line test (SELT). 9. The method of claim 8, wherein the first measurement technique is a metal line test (MELT) and the second measurement technique is a dual end line test (DELT). 9. The method of claim 8, wherein the first measurement technique is a single-ended line test (SELT) and the second measurement technique is a dual-ended line test (DELT). . Measuring a third predetermined line characteristic according to a third measurement technique (DELT / MELT / SELT);
Combining the measured first predetermined line characteristic, the second predetermined line characteristic, and the third predetermined line characteristic to derive a global line characteristic of the line therefrom. The method according to claim 8.   9. A method according to claim 8, characterized in that the end of the telecommunication line is located at a telecommunication access node location.   9. The method of claim 8, wherein the telecommunications line is a DSL telecommunications line.

Images